During June 2025, Dimitrios Economou developed parametrization and substitution support for CN programs in the rems-project/cn repository. He refactored core CN program handling and supporting modules to introduce a parametrized structure, enabling safer type checking and improved reuse of CN program patterns. By implementing cn_prog_sub_let, he facilitated substitutions within CN programs, allowing type checking of ghost arguments with substituted loads. This work, using ML and leveraging expertise in compiler development, functional programming, and type systems, laid the foundation for scalable and maintainable CN workflows. The depth of the refactor supports future extensibility and enhances the reliability of CN program validation.